1. Field of the Invention
The present invention relates to lightning protection and more particularly, preventing sparking and arcing inside composite fuel tanks when subjected to lightning.
2. Background
Fuel tanks are typically used to carry and store fuel in various transportation systems, including aircrafts. The environment inside fuel tanks is hazardous. Lightning attachment to fuel tank skins can result in a catastrophic failure. Lightning channels are very energetic and when lightning attaches to gaps and interfaces, it has to flow freely through one joint and not another. Fuel tanks are being increasingly constructed of composite materials because they are light and structurally sound. The composite fuel tanks are not as conductive as aluminum, the typical material used for previously designed fuel tanks. Thus components mounted on composite fuel tanks are more susceptible to sparking and arcing when subjected to lightning components. Specifically, the parts of the fuel tank which are susceptible are the fuel access door, which grants access into each bay of the fuel tank, the wing fuel tank, the interface between the fuel access door and the wing skin structure and components mounted to the fuel tank.
Prior systems and methods for preventing fuel tank penetration use expensive electrical bonding features such as electrical conductive rings that are co-bonded with the composite skin and bonding clips. Bonding conductive rings in composite fuel tanks can be expensive and labor intensive. Additionally, cap or brush coat sealing of fasteners is required for fasteners that penetrate the fuel volume. To prevent catastrophic failures as a result of a lightning event, a cost-effective system and method are needed for preventing sparking and arcing within composite fuel tanks.